<mat-stepper>
  <mat-step>
    <ng-template matStepLabel>One</ng-template>
    <button matStepperNext>Next</button>
  </mat-step>
  <mat-step optional>
    <ng-template matStepLabel>Two</ng-template>
    <button matStepperPrevious>Previous</button>
    <button matStepperNext>Next</button>
  </mat-step>
  <mat-step optional>
    <ng-template matStepLabel>Three</ng-template>
    <button matStepperPrevious>Previous</button>
  </mat-step>
</mat-stepper>
